Effect Of Laminated Rubber Bearing Sliding On Seismic Response Of Small And Medium Span Highway Girder Bridges

Using laminated rubber bearing as a supporting member of medium and small span highway girder bridge in our country is very common,the bearing possible relative slip with the beam body when this kind of Bridges under seismic action.The bearing slip breaks the force transmission path between the upper and lower structure,and reduces the horizontal seismic force,which is the reducing effect of the seismic isolation.But the sliding of the rubber bearing can cause the relative displacement between the upper and lower structure,it may lead to girder falling and make adverse impact on the seismic resistance of bridges.In this paper,on the basis of domestic and foreign related research work,typical in domestic medium and small span highway concrete girder bridge as the research object.OpenSees based software,through the parameter analysis,systematically studied in longitudinal and vertical earthquake plate rubber bearing and sliding on the earthquake response of the medium and small span simply supported girder bridge and continuous girder bridge,And discusses the corresponding measures of seismic design.The main contents are as follows:(1)Using the method of orthogonal experimental design,select bridge spans and bridge deck width and height of pier three parameters,respectively designed 25 samples of simply supported girder bridge and 25 samples of continuous girder bridge.Based on the Opensees software,establish the corresponding finite element model of whole bridge structure,analysis the time history of bridges structure response under the action of El and E2 earthquake.(2)Analysis results show that under the effect of El earthquake,37%of simply supported girder bridge and 10%of continuous girder bridge appeared bearing sliding phenomena;Under E2 earthquake,100%of the simply supported girder bridge and 100%of continuous girder bridge appeared bearing sliding phenomenon.(3)Under E2 earthquake action,bearing sliding played an effective protection to the medium and small span highway bridges' bearing and lower structure:For simply supported girder bridge,bearing shear deformation reduced by an average of 57%,the pier bottom earthquake shear force and bending moment the average decrease of 47%and 45%respectively;Of continuous girder bridge,the bearing shear deformation decrease by 47%on average,the bottom of the pier earthquake shear force and bending moment the average decrease of 46%and 42%respectively.(4)Under E2 earthquake,sliding bearing a certain extent increased the relative horizontal displacement between the main girder and pier top(or abutment):For simply supported beam bridge and continuous girder bridge,the relative horizontal displacement between the girder and pier top(or abutment)increased by an average of 18%and 21%respectively.However,all the relative horizontal displacement between girder and pier top(or abutment)are not more than the current minimum beam end bearing length.And the collision force is increased by an average of 61%and 61%respectively.(5)Site conditions make an certain influence on the sliding bearing probability and the size of earthquake response of the structure:Under El seismic action,most of the simply supported girder bridge bearing sliding in class ? or ? field,while the continuous girder bridge bearing sliding all in class ? or ? court;In addition,no matter under El or E2 seismic action,seismic response of the simply supported girder bridge and continuous girder bridge present ?>site ?>site ?>site ? class venue.(6)In medium and small span highway bridge,this paper puts forward using bearing sliding to isolation and the seismic design concept to avoid the adverse effect of earthquake and some specific technical measures.